The present invention relates to switching systems for controlling the operation of machines and the like which are capable of selectively performing any one of a multiplicity of tasks. More particularly, the present invention relates to switching systems for controlling the operation of appliances which are capable of selectively performing any one of a multiplicity of predetermined cycles, each of the cycles comprising a plurality of individual operations. And, although not limited thereto, the switching system of the present invention is particularly adaptable to appliances having electronic control systems.
Present day automatic appliances are frequently designed to perform a variety of predetermined operating cycles. In most instances, a particular appliance will include a broad range of cycles designed to anticipate the needs of its user and will further include means for enabling the user to make selections from the available operating cycles. For example, in the case of an automatic dishwasher, the various operating cycles may be characterized by the types and number of individual operations, such as washes and rinses, performed as well as the length of time spent performing a particular operation or part of a cycle. In this regard, the various operating cycles are normally designated by names which are descriptive of their intended use. One such operating cycle might be designated the "Heavy Wash" cycle and may include, for example, three wash operations and five rinse operations. Another operating cycle might be designated the "Light Wash" cycle and may include only one wash operation and three rinse operations. Selection of a particular cycle from the repertoire of available cycles, is normally made by the user by means of switches on the control panel of the appliance.
In addition to a repertoire of basic operating cycles, present day appliances frequently include optional operating modes for use at the operator's discretion. Again considering an automatic dishwasher as exemplary, one such optional mode might contemplate the use of a thermostat controlled delay to assure that the water temperature reaches a certain level. This optional operating mode may be designated the "Sanitizing Delay" option. The selection of this and other optional modes is normally accomplished by means of control panel switches, similar to the switches used for cycle selection.
An appliance control system illustrative of the present day art is disclosed in U.S. Pat. No. 3,774,056, issued to Sample et al., on Nov. 20, 1973 and incorporated herein by reference. The Sample et al. patent teaches an electronic circuit for controlling the performance of a multiplicity of operating cycles. Each of the operating cycles includes a cycle-select input, which inputs may be selectively energized to initiate the corresponding operating cycle by a seven station interlocking push button switch. Other electronic appliance control systems employ rotary and toggle switches as means for selecting from the available repertoire of operating cycles. See, for example, U.S. Pat. No. 3,790,815 issued to Karkles on Feb. 5, 1974, and U.S. Pat. No. 3,464,673 issued to Cargo et al., on Sept. 2, 1969.
Prior art cycle-select switching systems of the type described above typically comprise relatively complex mechanical switching structures, frequently having mechanical interlocks to assure that only one operating cycle can be selected at a time. Complex switching structures of this type are relatively expensive and are prone to structural degradation due to the inclusion of numbers of moving parts. Moreover, as the repertoires of available operating cycles become increasingly more complex, and as more optional operating modes are added to the repertoires of basic operating cycles, the cycle-select switching systems of the prior art become correspondingly more complex and expensive.